The Universal Mobile Telecommunication Service (UMTS) standard provides a compatibility standard for cellular mobile telecommunications systems. The UMTS standard ensures that a user equipment (UE) operating in a UMTS system can obtain communication services when operating in a system manufactured according to the standard. To ensure compatibility, radio system parameters and data transfer procedures are specified by the standard, including protocols governing digital control messages and bearer traffic that are exchanged over an air interface.
The UMTS standards provide, in 3GPP TS 25.344 (Third Generation Partnership Project Technical Specification 25.344) v0.5.0, 3GPP TS 23.246 v2.0.0, and 3GPP TS 23.846 v6.1.0, for a provision of a Multimedia Broadcast/Multicast Service (MBMS) by a UMTS communication system to MSs serviced by the system and subscribed to the service. When a user equipment (UE) activates in a communication system that provides an MBMS service, such as a broadcast of audio, video, and/or data concerning a sporting event such as a Super Bowl or a World Cup soccer game, the UE may subscribe to the MBMS service by registering for the service with one or more of a Support Node and a Broadcast Multicast Service Center (BM-SC) serving the UE. By subscribing to the MBMS service, a UE joins a subscription group associated with the service.
When the serving BM-SC receives MBMS data associated with the MBMS service, the BM-SC forwards the data to a Radio Network Controller (RNC) serving the UE via the serving Support Node. In response to receiving the MBMS data, the RNC broadcasts an MBMS notification to all UEs serviced by the RNC. In response to receiving the MBMS notification, each UE that is subscribed to the MBMS service conveys a connection request, typically a Radio Resource Control (RRC) connection establishment request, to the RNC via an access channel and a corresponding Node B. Upon receiving the connection requests from each of the subscribed UEs, the RNC counts a number of responding UEs serviced by each Node B and sets up a communication session at each Node B by establishing a Point-to-Multipoint (PTM) communication channel or Point-to-Point (PTP) communication channels with each responding UE serviced by the Node B based on the number of responding UEs serviced by the Node B. Upon establishing the PTM communication channel or PTP communication channels at the serving Node B, the RNC conveys the MBMS data to the subscribed UEs via the established channel or channels.
A problem arises with respect to an efficient method of notifying a roaming MBMS user of the upcoming MBMS data transmission. When a subscribed UE has roamed to a visited network outside of the UE's home MBMS service area, that is, the service area of a home BM-SC with which the UE has registered for the MBMS service or that serves the Support Node with which the UE has registered the UE will not receive the MBMS service to which the UE has subscribed.
Therefore, a need exists for a method and apparatus that provides for provision of an MBMS service to a subscribed UE that has roamed outside of its home MBMS service area.